crank questions

[sangheraent]

alright I got a 89 bottom end with a 86 top end and I run a spacer plate. Can i put a stroker crank in there for more power and if I do will i need a diffrent spacer or how is this at all possible?

also i have a 38 a/s carb will the stock intake boot stretch to it or will i need a bigger boot?

[Honda 250r 001]

I think you need to run a 4mm spacer plate with a stroker crank, and a 86 piston... Its a pretty torquey set up, i had it set up like that once. But you should get it port matched for the increased stroke or it wont run much better.

[86 Quad R]

its not as simple as drop in a stroker crank en go.... the cylinder has to be port matched for the added stroke and if the cylinder is allready ported there is a remote chance that it wont work with a stroker crank.

edit: also, you should be real selective as to whom you chose to do the work aswell. not many peeps can do it and do it correct. besides there are a few different combo's that can be used.

[Honda 250r 001]

Originally posted by 86 Quad R
its not as simple as drop in a stroker crank en go.... the cylinder has to be port matched for the added stroke and if the cylinder is allready ported there is a remote chance that it wont work with a stroker crank.

imo a stroker crank is a bad idea. Its just not the ideal set up imo. I would get that cylinder ported or get a big bore.

[86 Quad R]

Originally posted by Honda 250r 001
imo a stroker crank is a bad idea. Its just not the ideal set up imo. I would get that cylinder ported or get a big bore.

do you have any reasoning as to why your opinion is swayed that way? and have you actually run a 4mil that was spot on? juss curious. :cool:

[8686]

Originally posted by 86 Quad R
do you have any reasoning as to why your opinion is swayed that way? and have you actually run a 4mil that was spot on? juss curious. :cool:

Because he has no idea what he is talking about.

[Honda 250r 001]

Originally posted by 86 Quad R
do you have any reasoning as to why your opinion is swayed that way? and have you actually run a 4mil that was spot on? juss curious. :cool:

Its just really tough to get a cylinder set up. any farther than a 4 mil and it gets even tougher...

[86 Quad R]

not any tougher than a standard stroke. as long as the "porter" gets the correct #'s in the port timing, there is nothing any different than dialing it in other than correctly matching the bolt on's that correspond to where the desired power band. :cool: i'm under the impression that you had a not so goed experience?

[Honda 250r 001]

well you just never know how its going to end up, there a bunch of ways to set it up! do you set it up so the piston still at tdc has zero heigth from the cylinder? You have to get special heads made to accomodate for the increase in stroke. Plus the 250r has a long enough stroke the way it is. The piston goes up 2 mm more and down 2 mm more, and you can only go up and down so much before the piston starts to come out of hte cylinder to far on the bottom and top... It would be a good set up if you could have a longer stroke cylinder made to match it imo. :/

[sangheraent]

well I know about the porting and stuff I was just curious. anyway how come alot of the 250r guys dont have strokers most of them just run 310s or 330s i never hear to many people say they have stroker cranks. im pretty deep into banshees and basically everyone and there mother rides a stroker but on this forum i dont see very many?

[86 Quad R]

thats largely due to the reasoning previously mentioned...... the R engine already has a great stroke from the get-go. although, the added aftermarket stroke(set up correctly) will deliver a wealth of torque, even on a smaller stock bore and still have some revs to it. :devil:

[machwon]

I've run a 4mm in my for the last two motor builds. Each time it adds 5 hp due to the extra displacement. I do porting and head mods so I know its done right. I've done them for others as well, stock cylinders, pro-x 310 and 330's. My winter motor project this year is a 4mm stroker, stock cylinder with a 72mm bore and a stock head. I'm going for a sleeper look, but people will probably know something's up after they see it run.